Combustion and Wikipedia:Introduction (historical): Difference between pages

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'''Combustion''' or '''burning''' is an [[exothermic reaction]] between a substance (the [[fuel]]) and a gas (the [[oxidizer]]), usually O₂, to release [[heat]]. In a complete combustion reaction, a compound reacts with an oxidizing element, and the products are compounds of each element in the fuel with the oxidizing element. For example:

<!-- Feel free to change the text below this line. No profanity, please. -->

Hello this is a try

CH₂S + 6 F₂ &rarr; CF₄ + 2 HF + SF₆ + heat

THIS IS AWESOME!!!!!

==Rapid combustion==

Rapid combustion is a form of combustion in which large amounts of heat and [[light]] energy are released. This often occurs as a [[fire]].

This is used in forms of machinery, such as [[internal combustion engine]]s, and in [[fuel-air explosive]]s.

==Slower combustion==

Slow combustion is a form of combustion which takes place at low temperatures. [[Cellular respiration|Respiration]] is an example of slow combustion.

==Complete combustion==

In complete combustion, the reactant will burn in oxygen, producing a limited number of products. When a [[hydrocarbon]] burns in oxygen, the reaction will only yield carbon dioxide and water. When elements such as carbon, nitrogen, sulfur, and iron are burned, they will yield the most common oxides. Carbon will yield carbon dioxide. Nitrogen will yield [[nitrogen dioxide]]. Sulfur will yield [[sulfur dioxide]]. Iron will yield [[iron(III) oxide]]. Complete combustion is generally impossible to achieve unless the reaction occurs where conditions are carefully controlled (e.g. in a lab environment).

==Incomplete combustion==

In incomplete combustion, where sufficient oxygen for complete combustion is lacking, the reactant will burn in oxygen, but will produce numerous products. When a hydrocarbon burns in oxygen, the reaction will yield carbon dioxide, water, carbon monoxide, and various other compounds such as nitrogen oxides. Incomplete combustion is much more common and will produce large amounts of byproducts, and in the case of burning fuel in automobiles, these byproducts can be quite lethal and damaging to the environment.

==Chemical equation==

Generally, the [[chemical equation]] for burning a [[hydrocarbon]] (such as [[octane]]) in oxygen is as follows:

:C_''x''H_''y'' + (''x'' + ''y''/4)O₂ &rarr; ''x''CO₂ + (''y''/2)H₂O

For example, the burning of [[propane]] is:

:C₃H₈ + 5O₂ &rarr; 3CO₂ + 4H₂O

The simple word equation for the combustion of a hydrocarbon is:

:[[Fuel]] + [[Oxygen]] &rarr; [[Heat]] + [[Water]] + [[Carbon dioxide]].

==Combustion phases==

The act of combustion consists of three relatively distinct but overlapping phases:

* '''Preheating phase''', when the unburned [[fuel]] is heated up to its [[flash point]] and then [[fire point]]. Flammable gases start being evolved in a process similar to [[dry distillation]].

* '''Distillation phase''' or '''Gaseous phase''', when the mix of evolved flammable gases with [[oxygen]] is ignited. Energy is produced in the form of heat and light, [[flame]] is often visible.

* '''Charcoal phase''' or '''Solid phase''', when the output of flammable gases from the material is too low for persistent presence of flame and the [[charring|charred]] fuel does not burn rapidly anymore but just glows and later only [[smouldering|smoulders]].

==Combustion temperatures==

Assuming perfect combustion conditions, such as an [[adiabatic]] (no heat loss) and complete combustion, the adiabatic combustion temperature can be determined. The formula that yields this temperature is based on the [[first law of thermodynamics]] and takes note of the fact that the [[heat of combustion ]] (calculated from the fuel's [[heating value]]) is used entirely for warming up fuel and gas (e.g. oxygen or air).

In the case of fossil fuels burnt in air, the combustion temperature depends on

* the heating value

* the [[stoichiometric air ratio]] <math>{\lambda}</math>

* the heat capacity of fuel and air

* air and fuel inlet temperatures

The adiabatic combustion temperature increases for higher heating values and inlet temperatures and stoiciometric ratios towards one.

Typically, the adiabatic combustion temperatures for coals are around 1500 deg C (for inlet temperatures of room temperatures and <math>{\lambda = 1.0}</math>), around 2000 deg C for oil and 2200 deg C for natural gas.

== See also ==

* [[Carbon dioxide]]

* [[Deflagration]]

* [[Detonation]]

* [[Fire]]

* [[Heat of combustion]]

* [[Phlogiston theory]] (historical)

* [[Pyrolysis]]

* [[Pyrophoric]]

* [[Smouldering]]

* [[Spontaneous combustion]]

* [[Stoichiometry]]

* Machines

** [[Cyclone furnace]]

** [[External combustion engine]]

** [[Internal combustion engine]]

** [[Rotary combustion engine]]

** [[Staged combustion cycle (rocket)]]

* Measurement techniques

** [[Calorimeter]]

** [[Coherent anti-Stokes Raman spectroscopy]] (CARS)

** [[Laser Doppler velocimetry]]

** [[Laser-induced fluorescence]]

** [[Particle image velocimetry]]

* Social applications and issues

** [[Cooking]]

** [[Global warming]]

** [[Immolation]]

[[Category:Combustion| ]]

[[Category:Chemical processes]]

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[[cs:Hoření]]

[[de:Verbrennung (Chemie)]]

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[[ko:연소]]

[[he:בעירה]]

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